I have a Motorola 922 receiver and recently noticed that channels 100 through 127 are not available. I get the "can't find channel, continuing to search" message. Everything else appears normal on C3 and other satellites.
Sounds like maybe the dish might be off a little. Have you tried to bump it east or west to see if it will get a lock. Mine does that occasionally, the actuater won't stop where it's supposed to and I'll get a reading like that. I'll bump it and it comes in. You may also need to get a rehit, which seems more likely. Sometimes for one reason or another, the 4dtv seems to lose some/all channels, and it takes a rehit to get them back. NPS has an On-Line hit for there subscribers. Maybe your provider does too. If not give them a call, a rehit doesn't cost anything. If they're not busy, it won't take long.